This invention relates to means in suspensions of vehicle seats for adjusting quality or stiffness of ride, and particularly to an adjustable assembly in a parallel linkage of a vehicle seat to change continuously the distance of the connection of an end of a shock absorber from an adjacent pivot of the suspension.
Conventionally, suspensions of vehicle seats include parallel linkages for guiding respective upper seat supports, and the heights of the seat supports are adjusted by changing positions of connections to helical springs or by changing pressure in air springs. For controlling quality or stiffness of ride, shock absorbers either as separate components or as parts of assemblies including the springs are commonly connected to the parallel linkages, and the locations of the connections of the shock absorbers to the parallel linkages are often fixed. When the connections to the shock absorbers are fixed, the shock absorbers cannot be adjusted to change the quality of ride to provide the most comfort for occupants of different weights riding over roads of different roughness.
Changing the quality of ride by changing the positions of coupling pins along a link of parallel linkage is shown in U.S. Pat. No. 3,806,075 issued to Klaus Sturhan on Apr. 23, 1974. The changing of the quality of ride by changing positions of a coupling pin does not provide ready, continuous adjustment for the quality of ride, and although the use of a continuous control mechanism is suggested, an obvious suitable control is not described nor made obvious. A continuous means of adjustment is shown in U.S. Pat. No. 3,194,531 issued to A. Langer on July 13, 1965, but since a spring and a shock absorber are contained in one assembly, adjustment of quality also requires separate adjustment of the spring to restore a particular height.